Telephone receiver



Aug. 31, 1926.

C. R. HANNA 'TELFIHONE REGETVER Filed March 1924 Fly. 2

III I WITNESS-ES:

INVEpTOR f/m/a/r ff m/ia.

BY M ATTORNEY CLINTON R. HANNA OF WILKINSBURG,

PATENT OFFICE.

PENNSYLVANIA, ASSIGNOR T6 WESTING- rrou'sE ELECTRIC annmrrncrunme COMPANY, A CORPORATION E PENNSYL- 'rELErnoNE RECEIVER.

Application filed March 29, 1924, Serial No. 702,746.

My invention relates to telephone "receiver devices and more particularly to telephone receiver deviceshaving means for avoiding'magnetic saturation of the diaphragm thereof.

- Oneobjectof my invention is to produce a telephone receiver device in which the magnetic flux produced by the fluctuating I i current, which is to 'be translated into sound 1 waves follows a different pathth rough the device than the path traversed by the permanent magnet polarizing flux.

Another object of m'y-invention is'to produce a telephone receiver device having magnetic poles symmetrically disposed with re- 7 spect to the diaphr'agm.-

Another object of my invention is to produce a' telephone receiver device in which the variable flux produced by the fluctuating current is passed through a path other than the permanent magnet material.

Another object of my invention is' to pro duce a telephone'receiver; device in which the variable magnetic fluxpasses through the diaphragm in a direction parallel to the plane thereof and in which constant flux V passes through the diaphragm in a direction x at right angles to theplane thereof.

In the prior art of the construction of telephone receivers, it has been customary to provide a permanent magnet, frequently of a U-shaped, with electromagnet windings upon the poles thereof, which poles were I placed near, to the surfaces of a ferrous ma- 36 terial diaphragm. This construction causes the permanent magnetic flux to pass through the material of the diaphragm substantially parallel to the plane thereof from pole to pole of the permanent magnet. The varying flux produced by varying currents in the electromagnet coils 'is then superin1- po'sed upon this steady permanent flux. In-

consequence, the total flux of the permanent magnet was limited to a value substantially below that which would produce magnetic nent magnet steels, especially those having the higher coercive force values, have a low incremental permeability. In consequence, of this fact, aless change in magnetic flux was produced by the fluctuating current than would have been produced'had the magneticcircuit been composed entirely of soft iron.

My invention produces a structure in which the flux of the permanentmagnet is passed through the diaphragm at right an- 65 gles thereto and small spots only of the dia-' 'phragm are subject to magnetic saturation" when powerful permanent magnets are used. My invention further allows the variable flux to pass through the diaphragm 'in a di-' rection substantially parallel to the plane thereof, whereby the minimum magnetic reluctance is afforded to'the' variable flux. My construction further provides -meau's whereby the variable flux is conveyed through a magnetic circuit other than the body of the permanent magnet, thereby avoiding the lower value of variable flux which would result from the low incremental permeability of the high coercive force steels.

By this means, I am able'to produce a telephone receiver device having a ferrous material diaphragm acted upon directly by the varying magnetic flux produced by the fluctuating electric current, in which a .much greater amount of energy may be higher coercive force/can be used. f

Other objects. and structural details of my invention will be apparent fromrthe following description when read in connection with the accompanying drawing in which Figure 1 is a skeleton plan" view of the elements of my invention,

Fig. 2 is a view in vertical section of the elements of my invention,

Fig. 3 is a view in vertical section of an embodiment of my invention taken across the line of the electromagnet coils, and

Fig. 4 is asimilar view taken at right angles to the plane of the section in Fig. 3.

Referring to Fig. 1 and Fig. 2, an annularv permanent magnet 1 may be made of steel having a suitable high coercive force.

Within the permanent magnet 1 is placed the diaphragm 2. The permanent magnet 1 is ,magnetized in such a way as to have a north pole at one point on its periphery and a south pole at a point diametrically opposlte. Pole pieces 3, 4, 5 and'6 are attached to the permanent magnet l'at the points of location of these magnetic poles. Pole pieces 3 and 4 are attached to the upper surfaceof the permanent magnet 1 and pole pieces 5 and 6 are attached to the lower surface thereof. 1 016 pieces 4 and 6 are held together.

' and a low reluctance magnetic path establishe'd between them bya clamping piece 7 Pole pieces 3 and 5 are likewise held together bya clamping piece 8. Pole pieces 3, 4, 5 and i :6 carry thereon the windings 11, 12, 13 and 14 respectively. p

Referring to Figs. 3 and 4, a structural embodiment vof my invention illustrated therein, comprises the structure illustrated in Figs. 1 and 2. The diaphragm 2 is held in place by magnetic material clamps 7 and 8, and also by clamps 15 and 16 as shown in Fig. 3. A sound. channel is formed by a conical piece 17. and its extension 18.,

. Holes are provided in the conical piece 17,

which is of non-magnetic material, for the, passage of pole pieces 3 and 4. containing case is also provided'consisting of an upper section 19 and a lower section20.; A horn 21, which is attached to the upper section 19, may be replaced by any suitable sound-conveying means.v 7

In the operation of my device, the permanent flux of the magnet 1 is conveyed from the north pole'to the south pole thereof. through two parallel paths. One "of these -pathsconsists ofpole piece 6, an air gap 23,"

- other magnetic circuit consists of pole piece 5, an air gap 26, diaphragm 2, an airgap 24, pole piece 3, and magnetic shunt 8. The connections of coils 11,12, 13 and 14 are such that the magnetic flux produced in the two paths'tends to flowin the same direction through the materialof'diaphragm2.

The permanent magn'etflux, or constant flux, thus passes through the diaphragm 2\ only at spots between pole pieces 3 and 6 and pole pieces 4 and 5, only'asmall amount of leakage flux passing through other por-. tions of diaphragm. 2. The varying flux produced by coils 11, 12, 13 and 14 likewise passes into the same small spots in the diaphragm, but it does not pass directlythrough. Instead, it is conveyed by the body of the diaphragm 2 from pole piece 4 to pole piece 3 and from polei piece 5 to pole piece 6. By\this means, the body of-the diaphragm 2 is .kept' relatively free from the steady flux and -'is left available for a maximum value of varying flux. It is therefore, possible to act upon the diaphragm2 by a much higher .value of varying fluxes without approaching magnetic satuation of the diaphragm material than is possible by the construction common in the prior art.

This construction produces one in which two paths are available for the varying flux havinga portion of their paths in common,

The common portion is the diaphragm.

Such a disposition is called a figure eight distribution.

Furthermore, the fact that the magnetic path. of the varying flux induced in pole ieces 3 and 5 by coils l1 and 13, is conveyed y magnetic shunt 8 rather than by the body of permanent magnet 1, and that the flux induced in pole pieces4 and 6 by coils 12 and 14 isconveyed through the magnetic shunt 7 rather than the body of permanent magnet 1, avoids the influence of the low incremental permeability of permanent magnet 1 upon changes in the varying fluxes. means, itis possible to use a magnetic material having a low incremental permeability which is usually concomitant with high coercive force, without the losses which would otherwise occur because of such low incremental permeability. 4 v

By this means, Ihave produced a telephone receiver device which is capable of handling larger energy input than .devices of the priorarts and which avoids many of the art.

- While I have shown but one embodiment of my invention in the accompanying drawings, it is capable of various changes and modifications without departing from the spirit thereof, and it is, desired, therefore,

that only such limitations shall be imposed prior art or sides of said diaphragm, and a horn cooper- 4 atmg therewith. Y

2. A telephone receiver device comprising in combination a diaphragm of magnetic material, a permanent magnet of material having ahigh coerci e force and a low incremental permeability, four electro-magnets having cores oflow incremental permeabillosses incident to construction of the prior By as amass-4,

ity attached thereto and disposed on opposite sides of said diaphragm.

3. A telephone receiver device comprising in combination a diaphragm, a soundchan;

nel cooperating therewith, a permanent magnet, four pole pieces attached thereto and disposed on opposite sides of said diaphragm whereby magnetic flux from said magnet is conveyed through said diaphragm substantially at right angles to the plane thereof, a plurality of electromagnetic windings upon said pole pieces adapted to cause a flux to traverse a path between said pole pieces, within said diaphragm, in a direction parallel to the plane thereof.

a. A telephone receiver device comprising in combination, an iron diaphragm, a soundconveying channel member and a permanent magnet having a high coercive force also cooperating therewith, four pole pieces having a high magnetic permeability attached to the poles of said permanent magnet, four electromagnet coils respectively mounted on said pole pieces, said pole pieces and coils being symmetrically disposed on opposite sides of said diaphragm, a containing case for protecting said diaphragm, magnets, coils and sound channel, and a horn operatively associated with said diaphragm and said sound'channel.

5. A telephone receiver device comprising a diaphragm, an electric circuit, a protecting and supporting case portion and a magnetic circuit having a portion traversed by constant flux and adapted to be energized with a varying flux by said electric circuit, said diaphragm being a portion of said magnetic circuit and being so placed with respect to v other portions of said magnetic circuit that part of it is traversed by varying flux only.

6. A telephone receiver device compris ing a diaphragm and a plurality of cooperating magnetic circuits adapted to be, traversed only by constant flux in certain portions thereof, and only by varying flux in certain other portions thereof.

7. A telephone receiver comprising a diaphragm, a source of constant magnetomotive force, a source of. varying magnetomotive force and a magnetic circuit for the constant flux traversing certain portions only of said diaphragm,. other portions of said diaphragm being traversed by the varying flux.

81 A telephone receiver comprising a diaphragm, means for impressing a constant flux and means for impressing a varying flux upon said diaphragm, the said means directing the two fluxes differently, whereby the paths of the fluxes within the diaphragm are different.

9. In a telephone receiver, a diaphragm, a

source of direct magnetomotive force, a mag- 

